Field of the Invention
The present invention relates to a method for producing magnetic resonance (MR) images wherein, for acquiring MR data, essentially only one point in k-space is sampled on the basis of an RF excitation pulse. The present invention also relates to a correspondingly designed magnetic resonance scanner.
Description of the Prior Art
For an MR scan, it is customary according to the prior art to fill so-called k-space, which corresponds to the Fourier transform of the signal measured in the image domain, with scan data. A memory organized as k-space is usually filled line-by-line by acquiring, on the basis of the same RF pulse, a series of k-space points along a line during readout. Apart from Cartesian line-by-line sampling, k-space can be filled along any trajectory, e.g. along radial or spiral trajectories. Always on the basis of the same RF pulse, a particular number of k-space points are acquired directly one after another on the respective trajectory during the same readout.
More rarely according to the prior art, so-called single point imaging (SPI) is used. Here the MR data is acquired in the k-space such that, on the basis of the same RF pulse, generally only one measuring point or rather k-space point is captured, so that during a repetition only a single k-space point (or only a very small number of k-space points compared to the number of k-space points of a k-space line) is acquired. The advantage of single point imaging is that it is extremely robust, as the encoding time (i.e. the time between excitation and data acquisition) can be maintained constant for all the k-space points.
However, the disadvantage of single point imaging is that it is very time-consuming. For example, to acquire the MR data at an isotropic resolution of 1 mm and a matrix size of 128*128*16, a scan time of 30 minutes may be required, which is much too long for everyday clinical practice.